Dark energy and cosmic curvature: Monte Carlo Markov chain approach

We use the Monte Carlo Markov chain method to explore the dark energy properties and the cosmic curvature by fitting two popular dark energy parameterizations to the observational data. The new 182 gold Type Ia supernova data and the ESSENCE data both give good constraints on the dark energy parameters and the cosmic curvature for the dark energy model w(0) + w(a)z/(1 + z). The cosmic curvature is found to be vertical bar Omega vertical bar less than or similar to 0.03. For the dark energy model w(0) + w(a)z/(1 + z)(2), the ESSENCE data gives better constraints on the cosmic curvature, and we get vertical bar Omega vertical bar less than or similar to 0.02.